black white processing
Since the image is in the computer's memory, you can hop from one processing menu to another without having to save the image between steps. For example, you might Stretch an image, apply a Median filter to smooth it, run a Gradient filter on it to enhance edges, then Save it to disk.
Remember, if you don't Save the image, and you leave the B&W Processing menu, the image just goes away and you have to start over. As long as you stay in the B&W Processing menu or any of its submenus, the image stays in the memory of the computer.